<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.5.1/jquery.js"></script>
</head>
<body>
  <a href="" id="jj">点我</a>


<script>
    $('#jj').click(
        function () {
            alert("hello,jquery")
        }
    )
</script>
</body>
</html>